Variable Interest and Unconsolidated Entities - Additional Information (Detail)		1 Months Ended				3 Months Ended				12 Months Ended
	Apr. 01, 2016 USD ($) Property	Nov. 30, 2016 Property	Oct. 31, 2016 USD ($) Property	Apr. 30, 2016 USD ($)	Apr. 30, 2015 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) Option Entity	Dec. 31, 2015 USD ($) Property Loan Entity	Dec. 31, 2014 USD ($)
Variable Interest Entity [Line Items]
Number of wholly-owned subsidiaries | Entity										3	3
Number of buy out options exercisable | Option										3
Maximum exposure to loss on investment						$ 41,300,000				$ 41,300,000	$ 45,100,000
Investments in unconsolidated entities						0				0	73,434,000
Investment in unconsolidated entity	$ 79,479,000										$ 73,400,000
Number of properties held for sale | Property											6
Contribution to unconsolidated entity				$ 5,800,000
Payment of mortgage loan										39,206,000	$ 529,893,000	$ 365,224,000
Gain on purchase of controlling interest in unconsolidated entity	$ 30,000,000					$ 0	$ 0	$ 30,025,000	$ 0	30,025,000	$ 0	0
Number of mortgage loans repaid | Loan											2
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Variable Interest Entity [Line Items]
Number of properties sold | Property		36
Net gain from sale of real estate										10,600,000
Subsidiaries
Variable Interest Entity [Line Items]
Payment of mortgage loan				$ 5,800,000
Intrawest Venture
Variable Interest Entity [Line Items]
Payment of mortgage loan											$ 54,600,000
Intrawest Venture | Majority-Owned Subsidiary, Unconsolidated
Variable Interest Entity [Line Items]
Payment of mortgage loan											$ 54,600,000
Ski and Mountain Lifestyle Properties
Variable Interest Entity [Line Items]
Number of properties held for sale | Property	7
Number of properties sold | Property											1
Ski and Mountain Lifestyle Properties | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Variable Interest Entity [Line Items]
Disposition fee			$ 0
Number of properties sold | Property			7								1
Net gain from sale of real estate			$ (800,000)
Intrawest Venture
Variable Interest Entity [Line Items]
Percentage of ownership interest acquired	20.00%
Revenues										9,400,000
Operating income (loss)										$ 3,700,000
Senior Housing Property
Variable Interest Entity [Line Items]
Disposition fee					$ 0
DMC Partnership | Majority-Owned Subsidiary, Unconsolidated
Variable Interest Entity [Line Items]
Investments in unconsolidated entities												$ 104,400,000
Company's ownership percentage sold					81.98%
Proceed from sale of interest in joint venture					$ 139,500,000
Gain on Disposal of Discontinued Operations					$ 39,300,000
Intrawest Venture
Variable Interest Entity [Line Items]
Investments in unconsolidated entities											$ 73,434,000
Ownership interest											80.00%
Minimum
Variable Interest Entity [Line Items]
Remaining three buy-out options expiration year										2030
Maximum
Variable Interest Entity [Line Items]
Remaining three buy-out options expiration year										2032